The present invention relates to a method and system for the treatment and analysis of depression or other disorders, and in particular, the present invention relates to a method and system for the treatment of depression that utilizes bio-feedback training based upon degree of left-right brain wave symmetry.
Two areas of subject matter may be considered relevant background for the present invention: biofeedback, and in particular EEG biofeedback, and EEG correlates of depression.
"Biofeedback" is a technique of making available to a person a record of one or more of his/her physiological activities to which he/she ordinarily does not have direct conscious access. A biofeedback technique may consist of measuring and recording a selected physiological variable and somehow communicating to the person the variable being measured on a moment-to-moment basis. For example, most people cannot accurately state their systolic or diastolic blood pressures on demand because these values are not available to conscious perception. To use biofeedback to make a person aware of his blood pressure, a pressure transducer could be surgically installed in the person's blood vessel and its voltage readout used to drive a meter whose needle the person could directly and consciously observe with his/her eyes.
Biofeedback therapy has been used to treat a variety of illness conditions with the use of various physiological parameters: e.g., hand-temperature feedback has been used to treat Raynaud's syndrome; EMG feedback has been used to treat neuromuscular disorders (pain, stroke, spasm); rectal sphincter tension feedback has been used to treat fecal incontinence, and so on.
"EEG Biofeedback" refers to the use of a subject's EEG activity as the physiological system that is used for biofeedback. "EEG" stands for electroencephalogram. An EEG is a graph showing voltage as a function of time, as this voltage is recorded from brain which generates it. The EEG is an always ongoing a series of waveforms (usually varying in frequency from 0.01 to 100 Hz) recorded from an electrode sensor placed on or in brain, or more typically, on the scalp surface. This scalp sensor is known to measure ongoing, spontaneous bioelectric signals generated by underlying cerebral cortex. In principle, all cognitive and other mental activities occurring in cortex are associated with specific bioelectric cortical activities. There are a variety of attributes or properties by which an EEG can be characterized. Amplitude, frequency, and rhythmicity (synchronous or frequency-recurrent versus asynchronous) are the most typical. Every lead (sensor) one can attach to the scalp is able to sense the EEG at that locus. Thus, one can speak of relative amounts of some activity between any specified pair of loci.
EEG biofeedback is relatively old. Nowlis and Kamiya summarized their 1960's experiments more than 20 years ago (Nowlis, D. P. and Kamiya, J. The control of electroencephalographic alpha rhythms through auditory feedback and the associated mental activity. In: The Nature of Human Consciousness, edited by Robert E. Ornstein, W. H. Freeman and Company, 1973, 387-396. Originally published in Psychophysiology, 6 (1970) 476-484). In those days, the thrust of EEG biofeedback was to train subjects to produce more alpha activity in single, central scalp locations. The aim was to provide relaxation, good-feeling, and a sense of wellness. This literature has led to relaxation therapies which are presently used to reduce stress in tense persons. Despite its fairly widespread usage, simple alpha-biofeedback-based relaxation is not an established psychiatric/therapeutic approach.
There are a few other reports in which investigators used single site EEG biofeedback for therapeutic effects. In these studies, the EEG activity subjected to biofeedback is somewhat more complex than in the older alpha literature. These newer approaches require subjects to generate more EEG of a given frequency and less of another frequency, or to increase two different frequencies at the same time. Mann, Lubar, Zimmerman, Miller, and Muenchen (1992) are concerned with curing children with attention deficit disorder (Mann, C. A., Lubar, J. F., Zimmerman, A. W., Miller, C. A., and Muenchen, R. A. Quantitative analysis, etc. Pediatric Neurology, in press, 1992). They train patients to produce more beta activity (&gt;13 Hz) and less theta (5-7 Hz), and have claimed great success. Peniston and Kulkosky (1991 and references) have reported that training persons to increase alpha and theta activity is good for a variety of ills, from alcoholism to post-traumatic stress disorder (Peniston, E. G., and Kulkosky, P. J. Alpha-theta brainwave neuro-feedback for vietnam veterans with combat-related post-traumatic stress disorder. Medical Psychotherapy, 4 (1991) 1-14). Tansey (1990) describes a therapeutic use for EEG biofeedback in which increased beta (14 Hz) at a single scalp site is used to allegedly improve cognitive function in learning disabled children (Tansey, M. A. Righting the rhythms of reason: EEG biofeedback training as a therapeutic modality in a clinical office setting. Medical Psychotherapy, 3 (1990), 57-68). There are a series of studies by Sterman and colleagues from the 1970's in which increased 12-14 Hz single site EEG biofeedback was used to treat epilepsy.
"EEG alpha asymmetry" refers to the relative amount of rhythmic (repeating) alpha (8-12 Hz) frequency in the left side of scalp relative to the right side. (Note an EEG lead requires at least two connections to complete the circuit: (i) the "active" site on scalp over the critical brain region generating the signal of interest, and (ii) a "reference" locus, a part of the patient which is neurologically "quiet," e.g., an earlobe or skin over the mastoid bone. Typically, a third electrode is connected between the subject at another "quiet" spot and system ground.)
There are a few published studies of EEG biofeedback where two-site symmetry was the training parameter used, however these were not therapeutically oriented. Peper (1971, 1972) did some early demonstration that indirect left versus right alpha biofeedback was possible to demonstrate, and that it might be used diagnostically to see what kind of psychological states go with the various, biofeedback-trained (a)symmetries (Peper, E. Comment on feedback training of parietal-occipital alpha asymmetry in normal human subjects. Kybernetik, 9 (1971), 156-158. Peper, E. Localized EEG alpha feedback training: A possible technique for mapping subjective, conscious, and behavioral experiences. Kybernetik, 11 (1972), 166-169).
Schwartz, Davidson, and Pugash (1976) reported that left-right parietal (not frontal) alpha (a)symmetry biofeedback control could be learned by subjects (Schwartz, G. E., Davidson, R. J., and Pugash, E. Voluntary control of patterns of EEG parietal asymmetry: Cognitive concomitants. Psychophysiology, 13 (1976), 498-504). Schwartz et al. go on to report that more "emotional thinking" tended to accompany some of the training modalities. Their aims were, like Peper's, to see if symmetry and asymmetry biofeedback were possible, and also, to learn what the "cognitive" concomitants of trained (a)symmetry were.
Depression may be considered a pathological mental state associated with pathological EEG activity. "EEG correlates of depression" refer to recordable signs in the EEG which correlate with and thus may be symptomatic of depression. Pollock and Schneider (1990) reviewed the literature on the topic of EEG correlates of depression in awake subjects and Kupfer and Frank (1984--cited in Pollock & Schneider's references) did the same task for sleeping EEG samples (Pollock, V. E. and Schneider, L. S. Quantitative, waking EEG research on depression. Biol. Psychiatry, 27 (1990) 757-780; Kupfer, D. J. and Frank, E. The relationship of EEG sleep to vital depression. J. Affect Dis., 7 (1984) 249-263). The bulk of this work establishes that, despite some inconsistencies, depressed subjects show characteristic frequency attributes from single site sets of recordings.
More relevant to present concerns, however, are a series of reports from Davidson's lab which describe EEG regional asymmetries as highly reliable correlates of depression. Henriques and Davidson, (1990) have reported that, in comparison to normal individuals, depressed individuals have an abnormal electroencephalogram (EEG) pattern involving more left than right frontal alpha power and/or more right than left parietal or temporal alpha power (Henriques, J. B. and Davidson, R. J. Left frontal hypoactivation in depression. Psychophysiology, 27 (1990), p. S38 (Supplement). (a) Henriques, J. B. and Davidson, R. J. Regional brain electrical asymmetries discriminate between previously depressed and healthy control subject. Journal of Abnormal Psychology, 99 (1990) 22-31.(b). Davidson, R. J., Schaffer, C. E. and Saron, C. Effects of lateralized presentations of faces on self-reports of emotion and EEG asymmetry in depressed and non-depressed subjects. Psychophysiology, 22, (1985) 353-364). Matousek (1991) has provided recent confirmation (Matousek, M. EEG patterns in various subgroups of endogenous depression. International Journal of Psychophysiology, 10 (1991) 239-243). Others have shown EEG asymmetry correlates of other emotion-related conditions (e.g., Wells, B. G. and Moore, W. H., Jr. EEG alpha asymmetries in stutterers and non-stutterers: Effects of linguistic variables on hemispheric processing and fluency. Neuropsychology, 28 (1990) 1295-1305; Rickman, M. D. and Davidson, R. J. Frontal EEG asymmetry in parents of behaviorally inhibited and uninhibited children. Psychophysiology, 28 (1991), p. S46 (Supplement); Tomarken, A. J., Davidson, R. J., and Wheeler, R. E. Resting frontal brain asymmetry discriminates individual differences in repressive-defensiveness. Psychophysiology, 28 (1991) p. S57 (Supplement); Allen, J. J., Iacono, W. G., and Depue, R. A. Regional EEG asymmetries in bipolar seasonal affective disorder before and after phototherapy. Psychophysiology, 28, (1991) p. S9 (Supplement)).
Accordingly, it is an object of the present invention to provide a biofeedback method for the treatment of depression based upon the characteristic asymmetric brain wave pattern associated therewith.
It is a further object of the present invention to provide a method and system for the treatment of a pathological condition of a patient that is characterized by any brain wave asymmetry.